Optical fibers connectors are used to terminate optical fibers. An optical fiber connector and a complementary optical fiber connector may be used to mechanically retain two optical fibers such that light carried by one optical fiber may couple into the other fiber to form a light-transmitting path between the optical fibers. A multitude of optical fiber connector types have been developed over the years for specific purposes. The well-known FC-type optical fiber connector for example offers high alignment accuracy with up to 500 mating cycles and finds application in the telecommunications field where a small misalignment between the optical fiber cores results in significant optical insertion losses. Other, lower cost optical fibers have also been developed. At least two categories of optical fiber connectors include physical-contact connectors and expanded-beam connectors. Physical contact connectors operate by bringing the cores of the two optical fibers that are to be interconnected into physical contact, and variously suffer from the need for high alignment tolerance and degraded lifetime after successive mating cycles. Expanded beam connectors such as disclosed in patent application WO2008/024604A2 typically include a lens at the face of each of the two optical fibers to expand the optical beam such that the interface between the two connectors occurs within the expanded beam region via an air gap. The expanded beam minimizes the impact of misalignment on the insertion loss of the connector, and the airgap alleviates the mechanical wear associated with physical contact connectors, thereby reducing the impact of trapped dust particles on the optical fiber end faces and improving the number of mating cycles.
The constraints of high mating cycles and low insertion losses placed upon conventional optical fiber connectors however typically increase the cost of optical fiber connectors. High connector costs may prohibit the use of such connectors in applications such as the medical field where optical fiber connectors may form part of a disposable device. In one exemplary application a so-called photonic needle disclosed in document “Estimation of lipid and water concentrations in scattering media with diffuse optical spectroscopy from 900 to 1600 nm”, J. Biomed. Opt. 15, 037015 (2010) by R. Nachabé, B. H. W. Hendriks, A. E. Desjardins, M. van der Voort, M. B. van der Mark, and H. J. C. M. Sterenborg”, uses optical fibers to deliver light and perform spectral sensing measurements at the tip of a needle in order to analyze tissue that is in contact with the needle tip. Owing to the complexities of sterilization, the needle device is typically discarded after a single use. Consequently a need has arisen for low cost optical fiber connectors for use in disposable optical device applications.
Furthermore, the ability to connect a multitude of optical components to optical fiber connectors has generated a need to determine whether a particular connector, and thus optical component, is connected to an optical system. In a particular example of the photonic needle in the medical field, there is a need to determine whether an approved optical fiber connector, and thus an approved photonic needle, is connected to an optical measurement console. The interconnection of such an optical sensing device with a non-approved connector may result in inaccurate or unreliable results. Consequently a need has arisen for the ability to verify whether an approved optical fiber connector is connected in the optical path of an optical fiber. Such may also find application in the general field of optical fibers. Conventional solutions to this issue include the development of bespoke connector shapes to ensure that an optical system can only be mated with an approved connector type.